小攻角时风力机翼型边界层特性的数值模拟

Numerical simulation of boundary layer characteristics of wind turbine airfoil with small angle of attack

通过求解三维不可压雷诺时均N-S方程,当雷诺数为3×106,攻角为0°时,研究了NACA0012翼型绕流的边界层厚度分布和边界层内流体切向速度的变化规律.研究发现,沿着翼型弦线方向,从前缘到后缘,边界层的名义厚度、位移厚度、动量损失厚度以及能量损失厚度均呈增大趋势,且数值均很小,四种厚度的最大值分别占翼型弦长的1.25%、0.36%、0.17%和0.29%;在边界层内流体黏性的影响明显,流体切向速度与其势流解的比值沿着翼型吸力面外法线方向先迅速增大,之后增长率逐渐减小,当法向高度大于边界层名义厚度后基本保持不变,呈现出典型的边界层速度剪切特性.

By means of solving three-dimensional Reynolds time-averaged equation of incompressible flow with Reynolds number of 3×106,the distribution of thickness of the boundary layer and the variation pattern of the tangential velocity in the boundary layer on NACA0012 airfoil with attack angle of 0 deg was studied.It was found by the investigation that the nominal thickness,displacement thickness,the momentum thickness,and energy thickness of the boundary layer would all exhibit a increasing trend from leading edge to trailing edge of airfoil and the four thicknesses would be very small.Their maximum value will be1.25%,0.36%,0.17%,and 0.29% of airfoil chord,respectively.Besides,the effect of the fluid viscosity will be obvious in the boundary layer,and the ratio of the tangential velocity to that of potential flow will increase quickly at first along the external normal of airfoil suction side,then its increase rate will gradually reduce,and at last will remain basically unchanged when the normal distance was greater than the nominal thickness of the boundary layer,showing the typical velocity shear characteristics.